Fiber liberation



A. E. MILLINGTON 1,857,317

FIBER LIBERATION Filed Feb. 2l, 1928 2 Sheets-Sheet 1 May l0, 1932.

May 10, 1932' I A. E. MILLINGTON FIBER LIBERATION Filed Feb. 2l. 1928 2 Sheets-Sheet 2 :ai: i i.

t @Quanten dan# Mw rammed May 1o, 1932 PATENT oFFlcE ARTHUR E. MILLINGTON, F OAKLAND,

MESNE ASSIGNMENTS, TO THE UNITED STATES OREGON, AS TRUSTEE CALIFORNIA, ASSIGNOR, -BY DIRECT AND NATIONAL BANK OF PORTLAND,

FIBER LIBERATION Application led February 21, 1928. Serial No. 255,885.

This invention relates to improvements in preparing fiber-containing material, such as sawmill waste, for subsequent fiber sep arating operations, 5 in certain respects upon the process and apparatus disclosed in an application for United States patent, filed May 26, 1927, by v Arthur E. Millington,

One of the objects/of Serial No. 194,288. the present invention 1o is to provide an improved method or process of removing from Wood and the like the gums, resins and other non-fibrous materials which bind the fibers together, so that the tibers may readily be operations. ile solutions of soda-ash and similar chemicals may be used if desired, one of the advantages of the improved method is that it makes it possible to get the desired results, i. e., freeing liber-containing material of the binders normally holding the fibers together, without the use of any of such chemicals, thereby producing a cooked or prepared stock containing long fibers which when separated are very strong and highly 95v suitable for making wall board and similar products.

Another ot the objectsof the invention is to provide a method of preparing iber makin stock which will preparev the stock for the subsequent fiber making o erations in a comparatively short time an at comparatively low temperatures, with a minimum eX enditure or waste of heat.

till another object is to` provide an apparatus and method for eiecting the removal of binding materials insuch a way that the stock will not be charred or discolored.

Another and important object is to provide an yapparatus which is satisfactory for .carrying out the proce in a convenient, economical and highly eflicient manner. In its broadest aspects the invention comprises the idea of cookinga raw material, such as wood waste, in a liquid, preferably pure water, and under pressure and the liquid to carry or wash olf the matter which has been dissolved in it. If the cooking is eectedin a stationary tank or digester, the effect desired can be obtained by causing and is an improvement separated in subsequentconstantly 4changing l a slow, continuous ilow of water through theA digester while the cooking is in progress. `However, because of its obvious advantages, it is preferred to use a rotary digester of the globe type, and the iow or circulation of water is eected by a novel construction which results 'in anintermittent iiow into and out ofthe digester to wash out the soluble matter substantially as fast as it is removed from the stock. This construction also effects what may be termed intermittent injections of steam into the digester to the heat necessary for cooking and to supply, in partat least, the internal pressure required to cause the apparatus to work most efficiently. However, as will be more clearly apparent later, the heat necessary to 'give the required temperature and pressure might supply,V

be supplied in some other way, such as by a steam jacket enclosing the digester, and a water injecting and ejecting mechanism, such as herein disclosed, employed to cause the desired intermittent circulation through the digester.` j

The digester used in the present instance is very large, being about eighteen feet in diameter, and in order toA effect a uniform distribution of heat and circulation of water the digester contains asystem of perforated distributing pipes projecting throughout the mass in the digester.- In a stationary digester or tank these pipes might be driven, but in the rotary digester they are held lstationary and effect the distribution of the water and steam throughout the digester contents as the contents are carried past them by the rotations of the digester. L, Other objects and advantages will become apparent from the explanation hereinafter made and from an examination of the accompanying drawings which are repeatedly referred tol in and forml a part of this specification.

In said drawings: Fig. 1 is an assembled view partly in cros section showing the construction and relative arrangement of the parts of the apparatus. Figs. 2 and 3 are respectively a side view and a top plan View of one of the devices for operating the valve controlling the admission or injection of water into the digester.

12, supported on concrete posts or walls 13.

Rigid with one of the trunnions 11 is a gear 14 connected through a suitable set of transmission gears to a motor 15. The construction shown is preferably so proportioned and connected that the motor 15 will cause thel digester 10 to make a complete rotation eachy minute., but this speed is not essential and may be varied as desired.

The digester`10 is provided with a manhole 16 throughwhich supplies of the material to be treated may be introduced into the digester and diametrically opposite the manhole is a valve 17. This valve controls an opening'18 through which the liquid contents remaining in the digester are allowed to drain after the cooking opera-tion is completed. A screen 19, of perforated metal or any other suitable construction, holds back the material which has been cooked; After the cooking operation has been completed a flexible hose 21 or corresponding connection is attached to the valve 17 and conducts the liquid leaving thev digester to a sewer conc alignment.

nection 22.

After the liquid has been allowed to escape or drain from the shell 10, the cover for the manhole 16 is removed and the shell is given a half turn so as to bring the open manhole to a position under the shell, allowing the treated fiber-containing material to drop into a stock bin or upon a conveyor for carrying it to any point desired.

Extending through the trunnions 11 are two pipes 27 and 28. A division plate 29 between the ends of the pipes'is held in position by flanges 30'and 31 attached respectively to the pipes 27 and 28 and bolted together so as to -cause the pipes to be held rigidly in The division plate 29 prevents any communication directly between the pipes 27 and 28, and the construction just described causes the two pipes to serve as a unitary support for sets of perforated pipes 33 and 34 extending radially from the pipes 27 and 28. c y

rlhe perforated pipes 33 and the pipe 27 from which they extend are for the purpose of introducing steam into the digester and distributing it throughout the contents in an eilicient manner. The steam is carried by a header 37 which is large enough and of suliicient capacity to supply steam to a num-` ber of the digester or cooker units. Leading to each unit is aV steam pipe 38 provided at treated. The conduit or its lower end with a suitable fitting to ac commodate a drain valve 40 and a connection 41 to a valve 42 which may be opened or closed to admit or shut off the steam from the unit. Connected to the valve 42 is a reducing valve 43 of a form well known on the market, which may be adjusted to cause automatically any pressure desired within the digester 10. The control valve 43 is preferably of the kind equipped with an oil-pot or similar device to prevent fluttering in operation. Connected to the reducing valve 43 is a standard swing check valve, the swinging member 44 of which will act to close the passageway if for any reason a flow of steam or liquid shouldistart outward from the digester 10 through the pipe 27. Surrounding the pipe 27 is a standard packing gland 45 for vei'ecting a close relation. between the trunnion 11 and the pipe 27 to prevent leakage of the contents of the digester.

The pipe 27 is rigidly held against rotation by its connection with the swing valve and steam transmission mechanism described, with the result that the perforated pipes 33 are caused to serve not only to distribute the steam through the contents of the digester, but also to act as stirring rods or agitators for the contents of the digester while the digester is rotating.

The pipe 28 and perforated tubes 34 are for the purpose of introducing hot wate into a digester. The pipe 28 and adjacent trunnion 11 have a cooperating packing gland 51 to prevent leakage through the trunnion or around the pipe and the end of the pipe is connected to a fitting 52 equipped with a standard globe valve 53, which may be opened by hand to draw oil' some of the liquid contents of the digester whenever for any reason such an operation is found necessary. Above the connection 52 and communicating therey with, is a swing valve 54 which is the same in construction and operates vfor the same purposel as the valve l44 previously mentioned. The swing valve 54 is connected by a suitable piping to a valve designated generally by the numeral 55, Fig. 1, and which is hereinafter described in detail. The valve 55 is suitably connected to a hot water header 56. A globe valve 57 is available to shut off the flow of hot water from the hot water header 56 to the digester 10 whenever desired.

Attached tothe exterior of the digester is a bracket 61 comprising a conduit'62 leading from the interior of the digester. On the inner surface of the digester is a screen 63 of any suitable construction to hold back thek fiber-containing material which is being pipe 62 is provided with a valve 63 which is periodically opened as hereinafter described to permit some of the contents of the digester to escape through a short pipe 64 into a trough 65 which in turn i and as a seat for one end ofa spring 80.

' the under side of the iiexible plate 87.

drains through a pipe 66 into a tank or receptacle from which it may, if desired, be passed through a re-heating operation and again transmitted through the hot water header 56 to the system of digesters.

On the interior of the digester is a stationary bulb 71 o f the usual .type connected to a tempgerature` recording instrument 72 by a ilexi le tubing 7 3- of a well known type. The tubing 73 may extend axially through the hot water pipe 28 and connection 52. The recording instrument 72 comprises the usual time chart and marking instrument 74 for making a record of variations oftemperature over a definite period of time.

The valves 55 and 63' are substantially the same in construction and operation, and a description of the valve 55 will, therefore, suflice for both.

The valve 55 is operated to admit an injection of hot water at each rotation of the digester 10. It comprises a cap 77 having an internal shoulder (Fig. 4) engaged by a d 79 Attached to the rod 79 is a collar 81 working against the end of the spring 80. Integral with the collar or disk 81 is a spacing collar 82, one end of which abuts a valve member 83, attached to the rod 79, and normally held by the spring in position to close an opening 84 through which the hot water passes when the valve is opened.

Journaled in a forked member on the outer end of the rod 79 is a short shaft or rod 85 rotatably supporting a roller 86. During each rotationof the digester a member 87 moving with the digester will act against the roller 86 to\cause an endwise movement of the rod'7 9 against the tension of the `spring 80 to unseat the valve member 83 -and allow hot water to pass through the valve opening 84 from the hot water header 56 to the pipe 28 and tubes 34 within the digester. The member 87 is a flexible steel plate secured at its ends to posts turn secured to a plate 90. Extending through the plate 90 is a bolt 91, the upper end of which carries a member 92 engagillg y turning the bolt 91 and securing it in position by means of the locking nut 93, the plate 87 mayv be flexed to give different extents of movement to the rod,79, thereby causing the disk 78 which serves as -a guide for a ro valve 83-84 to open to the extent necessary amount of water to enter v to cause the desired the digester at eac The plate 90 is 95 extending from rotation of the digester. held in position by bolts bosses 96 on the digester and equipped with lock nuts 97 and 98 Whereby the'plate 90 and, of course fthe 'iiexible plate 87, may be adjusted and lield different distances from the digester shell. r'lhe nuts 97 and 98 may, therefore, be `used both to get `the proper relation of parts in assembling'and tates with described in detail 'f above.

`89- which are in `escape through to supplement the adjustment of the plate 87 to regulate the movements of the valve 83-84. l

The valve 63 is, as before stated, substantially the same in construction as the valve 55 just described in detail. However, it rothe digester shell 10 and the member for operating it is mounted upon one of the adjacent posts or walls supporting the apparatus. The operating member is designated generally by the numeral 101, Fig. l, and is substantiallythe same in construction as the mechanism shown in Figs. 2 and 3 and However, vany other suitable device for causing the openingof the relief or escape valve once during each turn of the digester may be employed.

The hot water in the heater 56 is under suffi`cient pressure to cause an injection of water whenever the valve 55 is opened and the interejection when the valve 63 is opened.

Preferably the valve 55 and the operating member 101 for the valve 63' are so positioned with reference one tothe other that the two valves will be opened simultaneously, or substantially so, although it has been found that the apparatus as a whole works for its intended urpose in a fairly eilicient manner when tiiis simultaneous j operation of the valves is'not adhered to.

In using the apparatus the digester 10 is lled up through the manhole 16 with sawmill waste including the normal percentage of bark prepared by chipping and re-chipping to reduce the pieces to a size which will pass through a 'screen used for rejecting pieces of material which are too large to be satisfactorily handled inthe digester. The digester is then illed up with water which preferably cals and the manhole 16 is then closed. The regulating valve 43 is then adjusted to give about fifty pounds pressure to the square inch in the digester and the valve 42 opened, after which the rotation of and maintained for a period of about one half of an hour. During this ti e it is pre'- ferred to keep-valves 55 and 6 prevent the operatmgplate 87 from opening.

the valve 55, and by making a similar adjustment in the device 101 for operating the valve 63.

After the desired temperature is obtained the valve openers 87 and 101 are set so that the valves 55 and 63'will befo each rotation of the digester. a result o contains none of the usual chemithe digester is startedl both closed so that the a plied steam will raise the connal pressure in the digester 10, due to the water pressure and steam pressure, causes an ened idurin this operation of the valves, a portion of the liquid contents ofthe digester is allowed to the valve 63 intothe 65 at each rotation and at about the same time an injection of fresh hot water is made through the valve 55. This causes an intermittent circulation of water through the digester, so that the resin and resin gums and corresponding matter removed from the woody material is carried away and the liquid replaced by fresh water coming in Each time that the hot water is discharged through the valve 63 and fresh water injected, the temperature and pressure in the digester will be lowered, thereby causing the valve 43 to` operate to admit a fresh supply of steam. There is, therefore, an intermittent flow of steam into the digester which is induced by the opening of the valve 63.

The water from steam condensation will,

. of course, cause the total volume of Water leaving through the valve 63 to exceed the inflow through the valve 55, such condensation water supplementing the incoming injections to wash out the non-fibrous matter cooked from the material in the digester.

It has been found that by using the apparatus shown and described, the resins and similar materials binding the fibers of the wood together can be dissolved and washed out in about six hours, thereby putting the contents of the digester in suitable shape `for subsequent operations such as set forth in application N o. l94,288 above mentioned. All of this lis preferably effected without using any soda ash, sulphite or corresponding solvents or digesting chemicals, leaving the fibers substantially free one from another and yielding long fibered `material unweakened by chemical treatment and 'admirably adapted for making wall board and similar materials.

Constant washing out of the dissolved matter and supplying fresh water to keep the digester filled is the ideal way of carrying out the process, but, as a practical matter, it is advisable, for some kinds of raw stock, to reheat the water leaving the digester and return it to the digester through the valve 55 if the soluble matter in it is not sufficient to interfere with further solution in the digester. Or, with such raw stock, the valve openers may be so regulated as to slow down the circulation in the digester and the water leaving through the valve 63 conducted directly to a Waste sewer or the like.

The fact that the cooking operations are carried on at comparatively low pressures and temperatures, and with the contents well covered by water, prevents charring or discoloration and contributes to the strength of the fibers in the final product.

While the container or vessel 10 is usually referred to herein as a digester, it should be made plain that the operation carried on in it `is not a digestion in the sense in which that term is usually employed. The pieces of material will have about the same sizes and shapes after they have been divested of the soluble matter as they had at the start and the term digester is, therefore, used largely as a matter of convenience. There will, of course, be some attrition and reduction because of the tumbling operation and because of the effect of the pipes 33 andl34, but it is negligible in amount. The pipes 33 and 34 are to effect thorough distribution of water and steam throughout the mass of contents and have little eect otherwise on the material.

At various points herein the terms cooked and cooking are used when referring to the material and the treatment of it in the digester l0. AHowever, these terms also are used largely as a matter of convenience, as the operation in the digester is not for the purpose of cooking in the ordinary sense. Its purpose is to soften the fiber-containing material throughout and remove from it substances which 'normally bind the fibers together, leaving any remainder of such substances in such softened condition as not to interfere with subsequent separation of the fibers.

. While the preferred apparatus and manner of carrying out the process herein described are admirably adapted to the purposes stated, it is obvious that either or both are capable of modifications and changes all coming within the scope of the claims which follow.

What is claimed is 1. In an apparatus of the character described, the combination with a rotary digester and means for rotating it, of means for automatically injecting hot water into the digester at each rotation of the digester, and means for automatically allowing a part of the liquid contents of the digester to escape at each rotation of the digester.

2. In an apparatus of the character described, the combination means for supplying steam to the digester, means for supplying water to the interior of the digester comprising a valve automatically and periodically operated to admit the water to the digester, and a valve automatically and periodically operated to allow water to escape from the digester, said valve being controlled by means operatively connected to the digester at predetermined points.

3. In an apparatus of the character describe the combination with a digester, of means for supplying steam to the digester, devices for supplying hot water to the digester comprising a valve automatically and periodically operated to admit the water to the digester, and a valv'e automatically and periodically operated to allow water to escape from the digester as water is admitted through the valve first mentioned, the actuation of the valves being controlled by means with a digester, of

of operative engagement with the digester at predetermined points.

4. In an apparatus of the character described, the combination with a rotary digester and means for rotating it, of means connected to supply steam and liquid to the interior of the digester, a relief valve in the wall of the digester, and means whereby each rotation of the digester will operate the relief valve to allow a portion of the liquid contents of the digester to escape, said relief valve being operatively connected to the digester at predetermined points in the travel thereof.

5. In an apparatus of the character described, the combination witha digester rotatablev on a horizontal axis and means for lrotating it, of means connected to supply steam and water to the digester, a relief valve for the digester located on the digester at a point removed from the axis of rotation thereof, and means for automatically operating said relief valve during each rotation of the digester and at .a predetermined point when said valve is below the axis of rotation of the digester to allow a portion of the liquid contents of the digester to escape.

6. In an apparatus of the character described, the combination of a rotary digester and means for rotating same, means for supplying steam under pressure to the digester,

- means for supplying hot water to the digester comprising a valve operable to admit the water to the digester, a valve for allowing water to escape from the digester, and devices for automatically operating said valves during the rotations of the digester, said devices being positioned at spaced oints on the digester whereby the valve will be actuated at predetermined intervals.

7. In an apparatus of the character described, the combination of a rotary digester and means for rotating same, means for supplying steam under pressure to the digester, devices for supplying hot water to the interior of the digester comprising a valve operable to admit the water tothe digester, a valve on the digester for allowing water to escape from the digester,and devices associated with the digester whereby each of said valves will be operated during each rotation of the digester, and at predetermined points to insure simultaneous actuation at predetermined intervals.

8. In an apparatus of the character described, the combination of a rotary digester and means for rotating it, means for supplying steam under pressure to the interior of the digester, means for supplying hot water to the digester comprising a valve adjacent to the digester operable to admit an in- ]ection of water, a member on the digester for operating the valve as the member passes the valve, a valve on the digester for allowing water to escape from the digester, and a stationary member for operating the last mentioned valve as said valve is carried past the member.

9. In an apparatus of the character described, the combination of a rotary digester and means for rotating it, means extending axially of the digester for conducting steam to the interior of the digester, means also extending axially of the digester for conductingwater to the interior of the digester, a valve for controlling the flow of the water, a relief valve on the digester, and means whereby both of said valves will be operated by the digester at predetermined points during the rotative travel thereof.

10. In an apparatus of the character described, the c ombination of a rotary digester and means for rotatingit, means extending axially of the digester for supplying steam under pressure to the interior of the digester, means extending axially of the digester for supplying water to the interior of the digester, perforated pipes extending radially of said axis for distributing the steam and water in the digester and serving as agitators for the contents of the digester, a valve in the water supply operable to admit an injection of water to the digester, a relief valve on the digester, and means for opening both of said valves during each rotation of the digester.

In testimony whereof I hereto aifix my signature.

ARTHUR E. MILLINGTON.

iso 

